You mind your own business. Maybe their family will reunite and this bedroom will still be available for their daughter. Chances are, you don’t know what is happening 100% with this family and you need to let them handle best what is best.
You can contact housing authority. They may already be aware or the situation and there are different types of situations in which family composition changes. It also has to be reported every year with financials to determine rents. More than likely, the tenant has already reported this situation and they are placed on a waitlist to downsize when another unit becomes available. But they also put hubbys and wives in seperate bedrooms, kids I think two and older if they are the same sex unless a med disability need to share the same bedroom--two to a bedroom.
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